EP2060755A2 - Valve driving mechanism unit in a combustion engine - Google Patents

Abstract

The component (1) has a housing (2) with a slave housing (4), which is firmly adapted to a recess (3). A slave piston (6) is movably supported in a borehole (5) of the housing. The housing is radially directed through a wall of the recess, and includes a front side (18) with a sealing surface, where the front side is turned towards a base (19) of the recess. A gap compensating element is arranged in a voltage stream between the front side and the base, where the element has a preset axial deformability for achieving complete sealing effect of the sealing surface.

Description

Field of the invention

The invention relates to a structural unit of a valve train of an internal combustion engine with hydraulically variable gas exchange valve actuation. The structural unit comprises a housing with a recess, a receiver housing fixedly fitted in the recess and a slave piston axially movably mounted in a bore of the slave housing. This acts on the one hand with a gas exchange valve and limits the other hand, extending in the bore receiving chamber, wherein the radially oriented by the wall of the recess slave housing has a bottom of the recess facing end face with a sealing surface which is at least indirectly clamped against the bottom of the recess.

Background of the invention

Such a unit is considered from the considered generic EP 1 344 900 B1 previously known. The structural unit proposed therein is a housing which can be mounted in the cylinder head of the internal combustion engine for receiving specific components of a hydraulic valve train, which are required for the variable transmission of a cam lift to the gas exchange valve according to the known lost-motion principle. Specifically, these components are an encoder housing with a guided therein and a donor chamber limiting master piston as nockenseitigem drive, the valve-side slave housing with the slave piston as valve-side output, connected to the master chamber and the slave chamber, electrically controllable hydraulic valve for time-variable Absteuern of Hydraulic fluid from the chambers and a pressure accumulator for intermediate storage of the hydraulic fluid.

The problem underlying the invention described below relates to the structural design of the valve-side output. Background of this problem is the need to be able to precisely control the closing time of the gas exchange valve under all operating conditions of the internal combustion engine regardless of the elevation of the cam and thereby not mechanically and acoustically acceptable closing speeds of the gas exchange valve. Since, as is known, the quality of the valve closing operation depends on a precisely metered volume flow of the hydraulic fluid flow, which flows off in a tight time window just before reaching the valve closing position only via a so-called hydraulic valve brake in the form of a throttle point from the slave chamber, unwanted leaks in the slave chamber to undefined leakage flows and consequently lead to a negative impairment of the valve closing operation, which then can only be determined with insufficient precision.

In the structural design of the valve-side driven side of an assembly according to the cited document, however, the risk of such leaks due to unavoidable component tolerances can be significant. The reason for this is that the receiver housing firmly fitted in the recess of the housing radially aligns with its outer lateral surface in the wall of the recess, so that the wall run tolerances of the bottom of the recess and / or on the outer circumferential surface the bearing of the driver housing related tolerances lead from the end face to a local gap between the frontal sealing surface on the front side and the bottom, the gap in turn causes an undefined outflow of hydraulic fluid from the slave chamber at the time of valve closing operation.

Although the gap could be closed as a precaution by further axial compression of the slave housing in the recess, but there would be the increased risk of unacceptably high deformation of the slave piston bearing hole and thus a jamming of the slave piston in the bore. In addition, this problem would be exacerbated by housing and Nehmergehäusewerkstoffe with different thermal expansion coefficients, for example, the housing would consist of an aluminum material with relatively high thermal expansion and the slave housing made of a steel material with relatively low thermal expansion and consequently the front of the slave housing at very low temperatures additionally would be clamped against the bottom of the recess.

Object of the invention

The present invention is therefore based on the object, a structural unit of the type mentioned in such a way that the above-mentioned disadvantage is eliminated by simple means. Accordingly, the assembly should be such that even with deficient and therefore less expensive manufacturable component tolerances of the effluent during the final closing phase of the gas exchange valve from the slave chamber hydraulic fluid flow is displaced only over the defined cross section of the hydraulic valve brake.

Summary of the invention

According to the invention, this object is achieved in that in the voltage flow between the end face of the slave housing and the bottom of the recess at least one gap compensation element with predetermined axial deformability to achieve an at least almost complete sealing effect of the sealing surface is arranged. In other words, all component surfaces clamped between the end face of the slave housing and the bottom of the recess should be braced against each other by elastic and possibly plastic deformation of the gap compensation element, at least as far as possible.

As will become apparent from the embodiments of the invention explained below, the gap compensation element may be, on the one hand, a component clamped between the end face of the slave housing and the bottom of the recess or the front side or the bottom itself, each with a specific surface design having a predetermined surface area elastic and optional plastic deformability is provided. On the other hand, it can also be a component which has only a predetermined elastic and optionally plastic deformability.

Brief description of the drawings

Figur 1

ein erstes Ausführungsbeispiel mit als Spaltausgleichselement dienender Tellerfeder;

Figur 2

ein zweites Ausführungsbeispiel mit als Spaltausgleichselement dienendem rechteckigem Ring;

Figur 3

ein drittes Ausführungsbeispiel mit als Spaltausgleichselement dienendem kreisförmigem Ring;

Figur 4

ein viertes Ausführungsbeispiel mit als Spaltausgleichselement dienender Quetschkontur am Boden der Ausnehmung;

Figur 5

ein fünftes Ausführungsbeispiel mit als Spaltausgleichselement dienender Quetschkontur auf einer bodenseitigen Stirnfläche eines Flansches eines Kappenelements;

Figur 6

ein sechstes Ausführungsbeispiel mit als Spaltausgleichselement dienender Quetschkontur auf einer ventilseitigen Stirnfläche eines Flansches eines Kappenelements;

Figur 7

ein siebtes Ausführungsbeispiel mit als Spaltausgleichselement dienender Quetschkontur auf der Dichtfläche des Nehmergehäuses und

Figur 8

eine als Referenz dienende, nicht erfindungsgemäße Ausführung der Baueinheit gemäß dem Stand der Technik.

Ausführliche Beschreibung der Zeichnungen Further features of the invention will become apparent from the following description and from the drawings, in which the embodiments are shown in each case partially simplified by reference to an essential for the understanding of the invention section of the assembly. Unless otherwise stated, the same or functionally identical features or components are provided with the same reference numbers. Each show in longitudinal section through the slave housing:

FIG. 1

a first embodiment with serving as a gap compensation element plate spring;

FIG. 2

a second embodiment with serving as a gap compensation element rectangular ring;

FIG. 3

a third embodiment with serving as gap compensation element circular ring;

FIG. 4

a fourth embodiment with serving as a gap compensation element crimping contour at the bottom of the recess;

FIG. 5

a fifth embodiment with serving as a gap compensation element crimping contour on a bottom end face of a flange of a cap member;

FIG. 6

a sixth embodiment with serving as a gap compensation element crimping contour on a valve-side end face of a flange of a cap member;

FIG. 7

a seventh embodiment with serving as a gap compensation element crimping contour on the sealing surface of the slave housing and

FIG. 8

a serving as a reference, not inventive design of the assembly according to the prior art.

Detailed description of the drawings

A first embodiment of the invention is in FIG. 1 disclosed. Shown is an output-side section of a structural unit of a valve train of an internal combustion engine with hydraulically variable gas exchange valve actuation, which is known to those skilled in the art, for example from the cited document cited. The preassembled and arranged in a cylinder head of the internal combustion engine assembly 1 comprises a housing 2 made of aluminum material, arranged in a hollow cylindrical recess 3 of the housing 2 The slave housing 6 made of steel material and a slave piston 6 axially movably mounted in a bore 5 of the slave housing 6. The slave piston 6, which is designed in several parts with a pressure piece 7 and a hydraulic valve play compensation element, interacts with a gas exchange valve 9 subjected to force in the closing direction and limits one with hydraulic fluid filled receiving chamber 10 which communicates hydraulically with a drive-side donor chamber 13 in the known stroke of the slave piston 6 and the gas exchange valve 9 in a known manner via channels 11 in the slave housing 4 and a 10 opening in the direction of the slave chamber 10 check valve.

The check valve 12 is part of an attached to the slave housing 4 and the slave chamber 10 limiting cap member 14, which is formed with an outer cap 15, an inner cap 16 inserted therein and a movably disposed between the outer cap 15 and the inner cap 16 and designed as a ball check valve body 17 in several parts is. In the cap member 14 is still an optional component of the assembly 1, as a valve distal end face 18 of the slave housing 4 may alternatively be clamped directly against a bottom 19 of the recess 3.

During the closing operation of the gas exchange valve 9, the check valve 12 is closed, ie, the check valve body 17 is in contact with the outer cap 15. After complete coverage of the channels 11 through the pressure piece 7 is only a throttled outflow of hydraulic fluid from the slave chamber 10 at a corresponding deceleration the gas exchange valve 9 possible. The throttled outflow of hydraulic fluid takes place both via an in FIG. 3 Both the slot 20 and the throttle bore 21 are known to serve as opening cross-sections of a so-called hydraulic valve brake, the one defined closing process of hydraulic generate variable valve trains from the sensor-side cam lift kinematically decoupled gas exchange valve 9. However, under all operating conditions of the internal combustion engine not only for reasons of mechanical component load and Ventiltriebsakustik, but also with regard to low closing time fluctuations within narrow limits to be observed closing speed of the gas exchange valve 9, however, requires a precisely observed opening cross section of the hydraulic valve brake both in cross-sectional size and, taking into account the interaction with the pressure piece 7, with respect to the axial cross-sectional position in the slave housing 4. Conversely, cross-sectional fluctuations of the hydraulic valve brake would lead to undesirably high deviations of the closing speed and / or the closing time of the gas exchange valve 9.

The underlying cause of such cross-sectional changes of the present invention is in FIG. 8 clarified, in which the structural conditions of the unit without inventive gap compensation element are shown enlarged. Accordingly, the undesired change in cross section may be, in particular, a wedge-shaped gap 22 between the valve-distal end face 18 of the slave housing 4 and a flange 23 of the cap element 14, which is greatly exaggerated here. The gap 22 is caused by geometric discontinuities due to unavoidable component tolerances and concretely by perpendicularity deviations of the slave housing 4 and the recess 3 in the housing 2. In detail, the end face 18 of the slave housing 4 is not ideally perpendicular to its outer lateral surface 24 and / or the bottom 19 of the recess 3 is not ideally perpendicular to the wall 25. Since the by means of screwing and / or pressing firmly in the recess 3 fitted slave housing aligned with its outer circumferential surface 24 on the wall 25 of the recess 3 radially, run in the general case, the end face 18 facing surface 26 of the bottom 19 and extending on the end face 18 of the slave housing 4 sealing surface 27 is not parallel to each other. Further pressing and / or screwing the slave housing 4 in the direction of the bottom 19 in accordance with local axial compression of the flange 23 in order Although closing the gap 22 would theoretically be possible, but would in nichtprozesssicherem assembly process of the slave housing 4, the risk of unduly high deformation of the bore 5 and consequently a clamping of the slave piston 6 (see FIG. 1 ) in the bore 5.

Inventive gap compensation elements that compensate for the deviating from the ideal component geometry discontinuities, in particular due to the aforementioned perpendicularity tolerances and lead to an almost complete sealing effect of the sealing surface 27 of the slave housing 4 are below in various embodiments with reference to FIG FIGS. 1 to 7 explained.

At the in FIG. 1 illustrated gap compensation element is a clamped between the bottom 19 of the recess 3 and the flange 23 of the cap member 14 plate spring 28, the biasing force is so high that it seals the flange 23 at all occurring pressure conditions in the slave chamber 10 plane-parallel against the sealing surface 27th (please refer FIG. 8 ) of the slave housing 4. Notwithstanding the illustrated individual spring may be, for example, a disc spring package or a helical spring.

In the FIGS. 2 and 3 are each formed as a ring 29 and 30 formed gap compensation elements, which are also clamped between the bottom 19 of the recess 3 and the flange 23 of the cap member 14. The rings 29, 30 differ in their cross-sectional shape, wherein the ring 29 is a rectangular ring, while the ring 30 has a circular or oval cross-section. The cross-sectional shapes mentioned refer to the undeformed state of the rings 29, 30, ie, when the housing 4 is not yet fitted in the housing 2. Elastomeric materials as well as metallic materials, such as aluminum or low-alloyed steels, may be provided as annular materials.

In the gap compensation element according to FIG. 4 it is a radially height-adjustable squeeze contour 31, which is formed as a circumferential bead on a sealing surface 27 facing surface 26 'of the bottom 19 itself. While the flange 23 of the cap member 14 is clamped with flat end faces 32 and 33 between the end face 18 of the slave housing 4 and the bottom 19 and the bottom end face 32, the bead 31 elastically and possibly plastically deformed, has a different cap member 14 'according to FIG. 5 a the bottom just formed 19 of the recess 3 facing end face 32 'with a radially height-adjustable squeezing contour 34 as a gap compensation element. Analogous to the embodiment according to FIG. 4 the crimping contour 34 of the flange 23 is formed as a circumferential bead, which is clamped under elastic and possibly plastic deformation against the bottom 19 of the recess 3.

Further exemplary embodiments of the invention are finally the FIGS. 6 and 7 removable. At an in FIG. 6 shown cap member 14 "has a valve-side, ie the sealing surface 27 of the slave housing 4 facing end face 33" of the flange 23 a radially height-adjustable, circumferential crimping contour 35 as a gap compensation element. The squeeze contour 35 is formed as a flat or spherical shaped and the flange 23 in this exaggerated representation outwardly tapering chamfer.

In FIG. 7 the sealing surface 27 of the slave housing 4 has a radially height-adjustable crimping contour 36 as a gap compensation element. This squeezing contour 36 is likewise a chamfer formed on the entire end face 18 in a plane or convex manner and sloping radially outward. When the slave housings 4 are executed, a drop of the chamfer 36, exaggerated here, of only 0.1 mm or smaller would have to be provided.

List of reference numbers

1

unit

2

casing

3

recess

4

takers housing

5

drilling

6

slave piston

7

Pressure piece

8th

hydraulic valve clearance compensation element

9

Gas exchange valve

10

slave chamber

11

Channel in the slave housing

12

check valve

13

donor chamber

14

cap member

15

outer cap

16

inner cap

17

Check valve body

18

Front side of the slave housing

19

Bottom of the recess

20

Slot in the slave housing

21

throttle bore

22

gap

23

Flange of the cap element

24

Outer jacket surface of the slave housing

25

Wall of the recess

26

Surface of the soil

27

Sealing surface of the slave housing

28

Belleville spring

29

ring

30

ring

31

Quetschkontur

32

bottom-side end face of the cap element

33

Valve-side end face of the cap member

34

Quetschkontur

35

Quetschkontur

36

Quetschkontur

Claims (15)

Assembly (1) of a valve drive of an internal combustion engine with hydraulically variable gas exchange valve actuation, comprising a housing (2) with a recess (3), a housing (4) fixedly fitted in the recess (3) and a bore (5) of the housing ( 4) axially movably mounted slave piston (6), on the one hand cooperates with a gas exchange valve (9) and on the other hand in the bore (5) extending slave chamber (10), wherein the through the wall (25) of the recess (3) radially oriented slave housing (4) has a bottom (19) of the recess (3) facing the end face (18) having a sealing surface (27) which is at least indirectly clamped against the bottom (19) of the recess (3), characterized in that in the voltage flow between the end face (18) of the slave housing (4) and the bottom (19) of the recess (3) at least one gap compensation element with predetermined axial deformability to achieve at least almost complete sealing effect of the sealing surface (27) is arranged. Assembly according to claim 1, characterized in that the sealing surface (27) of the slave housing (4) has a radially height-adjustable squeezing contour (36) as gap compensation element. Assembly according to claim 2, characterized in that the crimping contour (36) of the slave housing (4) is formed as a flat or spherically shaped, radially outwardly sloping chamfer. Assembly according to Claim 1, characterized in that the base (19) of the recess (3) has a surface (26 ') facing the sealing surface (27) with a radially height-adjustable crimping contour (31) as a gap-compensating element. Assembly according to claim 4, characterized in that the crimping contour (31) of the bottom (19) of the recess (3) is formed as a circumferential bead. Assembly according to Claim 1, characterized in that the structural unit (1) further comprises a cap element (14, 14 ', 14 ") which is mounted on the driver housing (4) and delimits the slave chamber (10), the sealing surface (27) of the Slave housing (4) by means of a flange (23) of the cap member (14, 14 ', 14 ") against the bottom (19) of the recess (3) is clamped. An assembly according to claim 6, characterized in that an end face (32 ', 33 ") of the flange (23) has a radially adjustable, circumferential crimping contour (34, 35) as a gap compensation element. Assembly according to claim 7, characterized in that the crimping contour (34) of the flange (23) as a bottom (19) of the recess (3) facing bead is formed. Assembly according to claim 7, characterized in that the crimping contour (35) of the flange (23) is formed as a flat or spherically shaped, the flange (23) radially outwardly tapering and the sealing surface (27) of the slave housing (4) facing chamfer. Assembly according to Claim 6, characterized in that the cap element (14, 14 ', 14 ") is movably arranged with an outer cap (15) and an inner cap (16) inserted therein as well as between the outer cap (15) and the inner cap (16) and in the direction of the slave chamber (10) opening non-return valve body (17) is designed in several parts. Assembly according to claim 6, characterized in that between the bottom (19) of the recess (3) and the flange (23) of the cap member (14) clamped disc spring (28) is provided as a gap compensation element. Assembly according to claim 6, characterized in that between the bottom (19) of the recess (3) and the flange (23) of the cap member (14) clamped ring (29, 30) is provided as a gap compensation element. Assembly according to claim 12, characterized in that the ring (29, 30) consists of elastomer material. Assembly according to claim 12, characterized in that the ring (29) in the undeformed state has a rectangular cross-section. Assembly according to claim 12, characterized in that the ring (30) in the undeformed state has a circular or oval cross-section.

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